Load partition during hot deformation of AlSi12 and AlSi10Cu6Ni2 alloys: a quantitative evaluation of the stiffness of Si networks

An eutectic AlSi12 alloy contains a rigid 3D network formed by the eutectic Si in the as-cast condition, which disintegrates during solution treatment. Synchrotron tomography proved that a near eutectic AlSi10Cu6Ni2 alloy also exhibits a 3D network with higher and more stable stiffness due to the presence of aluminides that retain the initial as-cast microstructure during the solubilization treatment and increase the volume fraction of rigid phases. In order to evaluate the load borne by different phases during hot deformation, in situ synchrotron experiments were carried out revealing an underestimation of the load transfer from the soft alpha-Al matrix to the hard silicon 3D network in the AlSi12 alloy. By taking into account the additional stiffness introduced by the local interconnectivity, the stresses in different phases in the near eutectic AlSi10Cu6Ni2 alloy were calculated. Additionally, the analysis of the aluminide Al2Cu allowed to identify its influence in the global damage of the hybrid 3D network formed by the Si and aluminides in the near eutectic AlSi10Cu6Ni2 alloy.